Negatively charged polymeric interphase for regulated uniform lithium-ion transport in stable lithium metal batteries

Li metal anode (LMA) for practical Li-metal batteries suffers from safety hazards and capacity deterioration caused by its high reactivity and infinite volume change. Herein, a stable LMA with highly uniform surface potential distribution was demonstrated by coating Li with a negatively charged artificial solid electrolyte interphase (ASEI), which is formed by spontaneous in-situ polymerization of 2,3,7,8-tetrakis((trimethylsilyl)ethynyl)pyrazino[2,3-g]quinoxaline-5,10-dione (PPQ) at room temperature. As an ion-transport regulator, such an ASEI with negatively charged moieties provides preferential Li-ion transport with high Li-ion transference number (tLi+ = 0.74). As a robust artificial layer, the PPQ-stabilized Li (PPQ-Li) maintains high mechanical strength (Young’s modulus of 7.39 GPa) after being immersed in electrolyte, which readily suppresses formation of hazardous Li dendrites and diminishes parasitic reactions on LMA, leading to dendrite-free morphology after long-term Li stripping-plating tests. Such a multi-functional interphase could potentially promote more tailorable coating designs for practically durable LMA.